You're partway right, tubby.twins, all DCs can be hotwired to run in series or parallel.
However, from earlier Talkbass threads (and the Nordy forum), I seem to remember Mr. Nordstrand & co. do wind their pickups slightly differently for a specific voicing, probably to avoid the pickups from being too muddy (if you switch an otherwise parallel pickup into series) or from being too thin (by switching vice-versa).
Might be wrong, though, but there's a little voice nagging me from older threads that's the reason behind it. Might be too much caffeine, though.
